This application relates to the art of sewage treatment and more particularly to inlet and outlet baffle structures for use in conjunction with septic and other sewage treatment tanks. The invention finds particular utility in conjunction with molded plastic tanks having arcuate end walls and will be described with reference thereto. It will be appreciated, however, that the invention finds application in other treatment tanks which are constructed of concrete, concrete block, plastic, metal, and other materials and which are configured in rectangular prisms, cylinders, spheres, and other shapes.
Most commonly, the inlet and outlet baffles of septic tanks comprise generally T-shaped structures. Specifically, the stem of the T connects with the horizontal inlet or outlet pipe. The cross bar of the T commonly extends into the air space at the top of the tank to act as a vent and extends below the scum layer into the liquid or clear zone of the tank. The inlet baffle functions to drop the incoming sewage directly in the liquid or clear zone of the sewage treatment tank. The outlet baffle functions to block the scum from being discharged into the disposal field. Rather, liquids from the liquid or clear zone of the septic tank are drawn off by the outlet baffle for distribution through the disposal field.
It has been recognized that the gas bubble rising in the liquid or clear zone of the septic tank should be prevented from entering the outlet baffle to reduce the flow of suspended solids into the absorption field and slow soil pore clogging. This has been achieved by disposing a deflector below the outlet Tee, by fastening a special outlet box projecting outward from the side of the septic tank wall, or the like.
One of the problems with the prior art septic tank structures has been the turbulence in the liquid or clear zone caused by the entrance of incoming sewage and the discharge of treated fluids. Such turbulence tends to interfere with the normal settling of sludge from the liquid in the clear zone. The turbulence tends to hold particles suspended in the liquid.
Further the turbulence and relative placement of the inlet and outlet baffles have tended to allow shortcircuiting of raw sewage from the inlet directly to the outlet baffle. In shortcircuiting, raw or partially treated sewage is discharged into the distribution system too quickly for the anaerobic bacteria in the clear zone of the septic tank to treat it properly and for settling to occur.